Baby sleep regression: understanding it and getting through it
A sleep regression is a temporary phase in which a baby who was sleeping reasonably well starts waking at night again. It mostly happens around 4, 9 and 18 months, and almost always goes hand in hand with a developmental leap. It lasts days or weeks, and the way through it is to keep your usual routine rather than change everything.
Your baby was sleeping reasonably well, and for the past few days they've been waking three times a night, wanting to be held and cutting their naps short. Nothing has changed at home, yet everything has changed in their sleep. The baby sleep regression is badly named: it isn't a step backwards, it's the knock-on effect of a step forwards. Here's what's happening, at what ages, and what to do from tonight.
What is a baby sleep regression?
A sleep regression is a short period in which a child who was sleeping steadily starts waking at night again, struggles to fall asleep or takes shorter naps, with no identified health cause. It almost always coincides with a developmental stage.
The word is misleading. Your child isn't losing any of the skills they had: their sleep is reorganising itself while their brain learns something else. Many sleep professionals actually prefer to call it a progression.
What's going on in the brain
A newborn's sleep alternates between two simple states. At around 3 to 4 months, it becomes organised into cycles closer to an adult's, with a phase of light sleep at the end of each cycle. Between two cycles, every sleeper briefly surfaces.
An adult drifts back off without remembering it. A baby, on the other hand, looks for the conditions in which they fell asleep. If they fell asleep in your arms, they'll want your arms. It's not naughtiness – it's a familiar cue that's missing at the wrong moment.
The second mechanism is learning. Rolling over, sitting up, crawling, pulling to stand, saying their first words: every new skill keeps the brain busy, night-time included. Plenty of parents find their little one practising crawling in the cot at 2 am.
A regression doesn't wipe out any skills. A child who could fall asleep on their own will be able to do it again, usually within days of the phase ending.
A baby who starts waking again hasn't lost anything. They've just learned something new.
How long does a sleep regression last?
A regression lasts days or weeks, not months. How long varies from one child to another, and above all depends on what you put in place during the phase.
Two things make it last longer. First, habits formed in a hurry: settling your baby back to sleep every night with a bottle or in your bed creates a new cue they'll ask for afterwards. Second, built-up tiredness, because an exhausted baby falls asleep less easily, never more easily.
If nights stay difficult well beyond a few weeks, if your child cries as though they're in pain, has a temperature or is eating noticeably less, it's probably not a regression. Speak to your GP or health visitor.
At what ages do sleep regressions happen?
Three ages come up in almost every parent's story: 4 months, 9 months and 18 months. There are other, more subtle phases too. No child goes through all of them, and some go through hardly any.
| Age | What's happening | What you see at night |
|---|---|---|
| Around 4 months | Sleep becomes organised into cycles | Frequent waking, very short naps |
| Around 6 months | Sitting up, new ways of moving | Waking with a need to move |
| Around 9 months | Separation anxiety, crawling | Crying when you leave the room, calling out |
| Around 12 months | First steps, first words | Taking longer to fall asleep |
| Around 18 months | Independence and saying no | Resisting bedtime, long wake-ups |
| Around 2 years | Imagination, fear of the dark | Repeated calling out, getting out of bed |
The 4-month sleep regression: the best known
It's the only one that reflects a lasting change. At around 4 months, the structure of sleep changes and won't go back to how it was. The other regressions are phases; this one is a turning point.
What you'll notice: naps that stop after a single cycle, frequent waking, a baby who opens their eyes as soon as you put them down. Evening bedtime, on the other hand, often stays easy, which makes the whole thing confusing.
Because sleep becomes lighter at the end of each cycle, household noises suddenly matter more. A door, the washing-up, the TV in the living room: what didn't bother them at 2 months wakes them at 4 months. A steady background sound masks these changes instead of letting them break through the silence.
An example White Noise Night Light for Babies 26 enveloping sounds, 15 volume levels, three brightness levels and six timer settings from 30 minutes to 3 hours. View the night light
Two limits worth knowing. White noise doesn't replace a regular sleep routine, and it should be kept at a low volume, with the device placed away from the cot rather than against the bars.
The 9-month sleep regression: separation anxiety
At around 9 months, your baby understands that you still exist when you leave the room. It's a huge step forward, and it's also what makes nights harder: night-time separation anxiety pushes them to check that you're still there.
At the same time, they're often learning to crawl and pull themselves up. They practise in the cot, end up clinging to the bars and don't yet know how to get back down. A 9-month-old's sleep then looks more like a series of short calls than long wake-ups.
What helps: a short goodnight routine that's always the same, games of peekaboo during the day, and going back in without switching on the main light. Go in, reassure, leave – in the same order every time.
The 18-month sleep regression: independence at stake
The 18-month sleep regression is different from the earlier ones. Your child walks, talks, says no, and discovers they can make decisions. Bedtime turns into a negotiation, and night waking comes with a specific request.
An 18-month-old's sleep is also disrupted by molars, by dropping from two naps to one, and sometimes by a new bed or starting nursery. Several causes pile up, which makes this phase harder to read than the one at 4 months.
At this age, children want to have an effect on the world around them. Letting them switch on their own light takes some of the heat out of the conflict, and this is when night lights designed for older children come into their own – ones they can put down, move and switch back on by themselves.
Our product pages are clear on this: a night light is useful from the very first nights because the parent is the one using it. Children can start handling it themselves from 18 months for one-piece soft silicone models, and from 3 years whenever there's a remote control, a button battery or a small part.
Other possible regressions (6 months, 12 months, 2 years)
At around 6 months, your child can sit up and is testing new ways of moving. At around 12 months, they walk and start to talk. At around 2 years, imagination arrives, and with it fear of the dark, which has nothing to do with the earlier regressions.
These phases are usually shorter and more subtle. They all follow the same pattern: visible progress during the day, disrupted nights for a while.
How to recognise a sleep regression
You can recognise a regression by three things: a sudden change in a child who was sleeping well, visible progress during the day, and no signs of illness.
Typical signs in babies
- Night waking that comes back after it had stopped
- Shorter naps, often ending after a single cycle
- Taking longer to fall asleep, with a strong need for contact
- Restlessness in the cot as your child practises their new skill
- Appetite and daytime mood that stay normal
- A clear start, within a few days, with no other explanation
Sleep regression or something else? (illness, teething…)
This is the question that matters at 3 am. The most useful clue is the daytime: a regression leaves your child full of beans during the day, whereas pain or illness leaves visible signs right through to lunchtime.
The pattern also helps you decide. A one-off discomfort is sorted with a single visit and doesn't come back the next night. Teething lasts a few days. A regression, on the other hand, settles in and repeats itself, often for one to two weeks in a row, with the same scenario every night.
If there's a temperature, unusual crying, refusal to feed or any doubt, the answer isn't in a blog post. Ask your GP, paediatrician or health visitor for advice.
What to do during a sleep regression
The principle fits in one sentence: get through the phase without creating new habits. Whatever you put in place during two difficult weeks, your child will ask for for months afterwards.
Mistakes to avoid
- Changing everything at once: new room, new routine, weaning, all in the same week
- Dropping a nap to tire your child out, which has the opposite effect
- Always rocking them back to sleep in your arms when you didn't before
- Putting them to bed later in the hope of a longer night
- Adding lots of new things to the cot: comforters, music, colour-changing lights
- Comparing with the neighbours' child – sleep patterns don't transfer
A more subtle mistake is expecting an object to fix the night. A night light doesn't put a child to sleep; it removes one reason to wake up and provides a steady point of reference. It's useful, but it isn't a solution.
Practical tips to support your baby
Keep the routine exactly the same
Same order, same place, same length. It's the only anchor that stays put while everything else changes.
Put them down at the right time
Watch for signs of tiredness – yawning, eye rubbing, a fixed stare – and put them to bed before they become overtired.
Leave a little leeway
Wait a minute or two at the first sound. Some wake-ups settle on their own if you don't open the door too quickly.
Always respond the same way
Low voice, slow movements, no bright light, the same phrase every time. Predictability reassures more than the time you spend.
Protect naps
A day with good naps sets up a calmer night. It feels counter-intuitive, yet it's what makes the biggest difference.
Share the load
Take turns getting up from one night to the next. A regression is easier to get through with two moderately tired adults than one exhausted one.
Then there's the unavoidable 3 am wake-up. You need to see without waking them, change a nappy or give a bottle without setting off an hour of being wide awake. The main light is the worst option, and so is your phone screen. What you need is a low, warm, adjustable light that you can carry with you.
Along those lines Portable Touch Night Light Brightness adjusted with a single touch, warm white or cool white, cordless and 200 grams, 22.5 hours of battery life. View the night light
Should you change the bedtime routine?
Generally, no. The familiar routine is exactly what reassures your child when everything else is shifting. You can make small tweaks – bringing bedtime forward by a few minutes on very tired evenings or stretching the wind-down time a little – without changing the order of the steps.
If you'd like to add a light to the room, introduce it before the difficult phase rather than during it. Something introduced in the middle of a rough patch becomes an event, and so one more reason to stay awake.
The soft silicone models in our baby night light range are designed to stay on all night at low brightness, so you don't have to switch something back on at every wake-up.
When does a sleep regression end?
A regression ends on its own, with nothing that needs treating. It stops once the skill that triggered it has been mastered.
Average length by age
The 9- and 18-month phases are passing stages. Nights settle again once the skill is mastered, often within one to a few weeks, and your child gets back to roughly the sleep they had before.
At around 4 months, it's different. The unsettled period passes, but sleep doesn't go back to how it was: it has become cyclical for good. What you gain on the other side is a child who gradually learns to link their sleep cycles on their own.
Signs the regression is over
Wake-ups become less frequent
One or two a night instead of four, then nothing regular.
Naps get longer
Your child links two cycles during the day again without waking.
Resettling comes back
They drift back to sleep on their own after a noise, without needing to call you.
Days calm down
Less grumpiness in the late afternoon, and a steadier mood.
One last thing, and it matters: the end of a regression isn't the end of night waking. A child can wake at night long afterwards because of a tooth, a cold, a room that's too warm or a bad dream. That's normal sleep for a child, not a relapse.
FAQ
At what age do baby sleep regressions happen?
The most common phases are around 4 months, around 9 months and around 18 months. Other, more subtle phases occur around 6 months, 12 months and 2 years. Every child follows their own rhythm: some go through all of these phases, others hardly any.
How long does a sleep regression last?
It lasts days or weeks, rarely months. How long depends on the child and on what's put in place during the phase: habits formed in a hurry, such as rocking your baby back to sleep in your arms every night, tend to make it last longer.
Does a night light help during a sleep regression?
A night light doesn't put a child to sleep and doesn't make a regression go away. It acts as a steady point of reference: it lets you deal with a wake-up without switching on the main light and reassures a child who is starting to understand that you're not there. Go for a low, warm light.
Should you change the bedtime routine during a regression?
Usually not. The familiar routine is exactly what reassures your child when everything else is shifting. Keep the same order, the same place and the same length. A minor tweak, such as bringing bedtime forward on very tired evenings, is plenty.
How can you tell whether it's a regression or teething?
A regression comes with visible progress during the day, such as rolling over, crawling or talking, and your child stays full of beans in the daytime. Teething comes with dribbling, red cheeks and a need to chew. If there's a temperature or unusual crying, ask a health professional for advice.
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